Geological Characteristics And Metallogenic Conditions Of Typical Cu-Ni Sulfide Deposits In East Tianshan,Xinjiang

The Eastern Tianshan Mountains located in the Central Asian orogenic belt is an important magmatic Cu-Ni sulfide metallogenic belt in China.There are a lot of Cu-Ni sulfide deposits found in this area,such as Huangshan,Huangshandong,Xiangshan,Hulu,Tulaergen,Tudun et al.In previous studies,the Huangshan Cu-Ni metallogenic belt is the main distribution area of Cu-Ni ore deposits,starting from the Tulaergen area in space,extending west to the Kumutage sand ridge,but not over the Kumutage sand ridge.Therefore,in the previous understanding,the Huangshan Cu-Ni metallogenic belt is considered by many scholars as the Eastern Tianshan Cu-Ni metallogenic belt.However,in recent years,a large number of Cu-Ni deposits(spots)have been discovered in west of Kumutage Sand.In this paper,deposits(spots)such as Lubei,Baixintan,and Yueyawan in the west of Kumutage Sand Ridge are selected as the research objects.By studying the location and structural conditions of the Cu-Ni sulfide deposits(spots)studied,Rock characteristics,rock geochemical characteristics,and geophysics and geochemistry were compared and discussed,and the geological characteristics and metallogenic conditions of the Cu-Ni sulfide deposits in the area were finally obtained.The tectonic background of the Cu-Ni sulfide deposits distributed west of the Kumutage sand ridge in the Eastern Tianshan belongs to the post-orogenic belt collision and extension stage,which creates a strong tectonic background condition for the formation of Cu-Ni deposits in this area;The production and distribution of the rock mass in the area are controlled by the fault structure,which is not related to the fold.These large faults and their secondary faults provide important structural conditions for the formation of the deposit;the rock bodies of the research deposits are all basic-superbasic The range of volcanism is characterized by small rock masses and obvious lithofacies facies differentiation characteristics.Gradual facies facies zoning and abrupt zoning are developed.The former is formed by magmatic differentiation,and the latter is formed by different magmatic intrusion stages.The characteristics of multiple phases in the phase,the lithofacies are in accordance with the characteristics of the lithofacies in the Cu-Ni sulfide deposits;the ore-bearing rocks in the Cu-Ni sulfide deposits(points)are mostly pyroxene and gabbro,Peridot gabbro,Peridot,peridotite,and pyroxene peridotite;ore minerals are mainly pyrrhotite,chalcopyrite,nickel pyrite,magnetite,etc.;the rock body develops a variety of and copper-containing sulfides Various mineralization erosion closely related to oxidation Variations,such as malachite,sericite,limonite,chlorite,serpentine,etc.In addition,tremolite,talc,and edenite,sodium hafnium Cyanite,nickel bloom,chlorite petrochemical,chloridite,silicidation,etc.,have a strong development degree,and various types of mineralization alterations are usually accompanied by the production.They are Cu-Ni sulfide deposits of magnesia-super-magnesia complex Favorable conditions for mineralization;different deposits(points)of rock have With different characteristics of low Ti and high Mg,as the rock mass differentiates and evolves,SiO₂,Al₂O₃,Na₂O,and TiO₂ decrease with the increase of MnO content,and TFe₂O₃ and MnO increase.Rock m/f values in the study area all belong to The iron series is conducive to the formation of Cu-Ni deposits.The distribution patterns of rare earth elements in different Cu-Ni deposits(spots)are similar to the trace element spider web diagrams.They all have slightly enriched light rare earth right-inclined characteristics,heavy rare earth and light The fractionation between rare earths is also obvious,with different degrees of weak europium anomalies.In addition,the large ion philophile element Sr and the high field strength element U are relatively enriched,while the high field strength elements Nb and Ta are relatively deficient;geophysical characteristics show High weight,high magnetic,high pole The low-resistance characteristics can provide a certain basis for finding complex magmatic Cu-Ni deposits in this area.Geochemical characteristics indicate that the anomalous element combination in the Cu-Ni deposits in this area is Cu-Ni-Cr-Co-(Au-Sb-As-Mo-Zn),the delineation area of the elemental anomaly combination is consistent with the surface basic-ultrabasic rock mass,and the elemental anomalous concentration area is obvious.This anomalous combination shows that the area west of Kumutage sand ridge has copper and nickel Good metallogenic potential;at the same time,the formation age of Cu-Ni sulfide deposits distributed in this area is mainly concentrated in 269-298Ma,which is the product of the same period as Cu-Ni deposits in Huangshan,Huangshandong,Xiangshan and Baixintan.